Immersion-type cryogenic freezers are used for processing food products to individually freeze things such as shrimp and the like. Immersion-type freezers are sometimes mated to a tunnel freezer so that initial freezing takes place by dipping the product, e.g. shrimp, into a bath of liquid cryogen, removing the product from the bath and conveying to a freezing or equilibrating apparatus, e.g. a tunnel freezer where the vaporized cryogen is used to final freeze the product after initial crust freezing. Air Products and Chemicals, Inc. of Allentown, Pa. sells such freezers with the immersion part being identified as a CRYODIP freezer and the tunnel portion being identified as a CRYOQUICK freezer.
One of the problems with using the combination of the immersion and an after treatment apparatus is the sampling of product as it exits the immersion freezer to determine the degree of freezing so that the speed of passage through the apparatus and other parameters of the said apparatus can be adjusted. Normally to take a sample the immersion freezer must be opened exposing the sample taker to the liquid cryogen, and cryogen vapors which in the case of the cryogen being liquid nitrogen can be potentially harmful to the worker and also result in upsetting the entire freezing process.